1. Field of the Invention
The invention relates to a charged particle beam device and a method of operating a charged particle beam device. Particularly, it relates to a focused ion beam device having a gas field ion source, in particular for imaging, inspecting, and/or structuring a specimen. Further, it relates to a method of operating a focused ion beam device for emitting during operation a focused ion beam including ions of a gas. More specifically, it relates to a method for cleaning the emitter tip of an ion beam device.
2. Background of the Invention
Technologies such as microelectronics, micromechanics and biotechnology have created a high demand for structuring and probing specimens within the nanometer scale. Micrometer and nanometer scale process control, inspection or structuring, is often done with charged particle beams. Probing or structuring is often performed with charged particle beams which are generated and focused in charged particle beam devices. Examples of charged particle beam devices are electron microscopes, electron beam pattern generators, ion microscopes as well as ion beam pattern generators. Charged particle beams, in particular ion beams, offer superior spatial resolution compared to photon beams, due to their short wave lengths at comparable particle energy.
Despite its improved characteristics with respect to brightness, source size and low energy spread, the stability of ion emitters has to be considered. Several mechanical stabilizing devices are known, such as a further connection of the emitter or special mountings.
Due to long-term use of the emitter and abrasion resulting therefrom, cleaning of the emitter and the surroundings is generally conducted. Thereby, an ultra high vacuum can be used which is typically better than 1.33*10−7 Pa (10−9 Torr) and in particular better than 1.33*10−9 Pa (10−11 Torr).
Furthermore, a heating method to reduce fluctuations which may result from contamination of the emitter can be conducted. By heating the emitter, contaminating particles may be released from the emitter and its surroundings. Thereby, it is possible to pump the released contaminating particles out of the emitter area and to improve the conditions of the vacuum.